This invention relates generally to improvements in the efficiency of airfoils over which air flows; and more particularly to control of boundary layer air flow over such airfoils.
It is known that airfoils operate more efficiently, as in producing lift, etc., if air flowing over an airfoil closely follows its shape. However, boundary layer air turbulence at the upper side of the airfoil typically prevents such desired flow. In the past, means to reduce such boundary layer air turbulence included pumps or other devices to pump air from the airfoil surface, and major changes in airfoil shape, reducing airfoil efficiency. Pumps and other known devices for this purpose require moving parts subject to wear, or failure and undesirably add greatly to cost and weight. Changes in airfoil shape, in flight greatly complicate airfoil construction.
There is need for improved means to overcome the boundary layer control problem.